Anatomy CH 11.5: Cardiovascular system - Blood Vessels

blood vessels

network of:

• arteries

• arterioles

• capillaries

• venules

• veins

that carries blood away from the heart, to the cells, and back again

arteries

strong elastic vessels adapted for carrying high-pressure blood

transports blood away from the heart

• pressure driven

become smaller as they divide and lead to arterioles

arterioles

small branches of an artery that leads to capillaries

get thinner as they approach capillaries

larger arterioles have walls like arteries —> consists of three layers

smaller arterioles have only endothelium, small # of muscle cells, thin layer of CT

lumen

area where blood flows

• in both arteries and veins

what is the difference in lumen between veins and arteries

veins are wider

arteries are more narrow

endothelium

in both veins and arteries

layer closest to the lumen

what kind of tissue is the endothelium layer

simple squamous epithelial

tunica media

smooth muscle and elastic fiber

thicker in arteries

precapillary sphincter

regulates pressure when shifting to capillaries

• opens capillary beds of skeletal muscles via vasodilation and relaxation during exercise

• lessens the blood flow to capillary beds of less important areas of body in order to give blood somewhere else via vasoconstriction and contraction

capillaries

BV with the smallest diameter

connect small arterioles to small venules

only a layer of endothelium

Permeability varies from one tissue to the next due to the size of the openings between cells

density varies from body part

• areas with high metabolic activity have higher densities

allows nutrients, gases, and wastes to be exchanged between the blood and tissue fluid

exchange in capillaries

constant exchange of respiratory gases, nutrients, metabolic wastes between capillaries and tissue via diffusion, filtration, and osmosis

depends on concentration gradient

• typically goes from high to low

more fluid leaves capillaries by filtration than return via osmosis

lymphatic vessels

pick up excess tissue fluid that is not picked up by capillaries and returned into circulation

blood flow in capillaries

blood with a high concentration of oxygen + nutrients enters capillaries

• these things diffuse into tissues

plasma stays in the blood bc of large size

what is diffused INTO capillaries

carbon dioxide (CO2) and metabolic wastes diffuse from tissue fluid into capillaries

hydrostatic pressure

How things enter capillaries

occurs from the pumping of the heart

generates force for the filtration of substances through capillaries

opposite pressure of colloid osmotic pressure

when is BP higher than colloid osmotic pressure in capillaries

at the arteriolar end of capillaries

this means filtration occurs the most here

when is BP lower than colloid osmotic pressure in capillaries

at venular ends of capillaries

reabsorption is greater here

where are capillary openings larger

kidney

intestines

endocrine glands

where are capillary openings smaller

muscle tissues

colloid osmotic pressure

pressure caused by the presence of plasma proteins that stay in the blood and draw water into capillaries

opposite force of hydrostatic pressure

three types of capillaries

continuous

fenestrated

sinusoidal

continuous capillaries

found in skin (dermis/hypodermis), muscles, NS

small gaps that allow small molecules to pass through

fenestrated capillaries

found in kidneys, small intestine, endocrine glands (hormones)

filters

has small pores that allow small molecules to pass through

sinusoidal capillaries

found in liver, spleen, lymph nodes, bone marrow, endocrine glands

has large gaps and pores that allow blood cells through

venules

lead from capillaries merge to form larger veins that return blood to heart

veins

carries blood back to the heart

• blood is low in oxygen

different from arteries because it has valves to prevent backflow of blood

BP is lower than artery

functions as blood reservoirs

• vasoconstriction of veins in times of blood loss can restore normal BP even after 25% of blood being lost to a hemorrhage

type of wall - artery

thick + strong

3 layers

1. endothelial lining

2. middle layer of smooth muscle + elastic CT

3. outer layer of CT

type of wall - arteriole

thinner wall than artery

3 layers

• smaller arterioles have an endothelial lining + smooth muscle tissue + small amount of CT

type of wall - capillary

single layer of squamous epithelium

type of wall - venule

thinner wall than arteriole

less smooth muscle + elastic CT

type of wall - vein

thinner wall than artery but similar layers

middle layer is thinner

has valves

blood pressure

force blood exerts against inner walls of blood vessels

• moves through lumen of arteries and arterioles

decreases with distance from heart

• arteries > arterioles > capillaries > veins

exists all throughout the cardiovascular system

refers to systemic arterial pressure (blood vessel pressure)

increases with age

where is BP highest? lowest?

highest in arteries

lowest in veins

highest farther away from heart

lower closer to heart

systolic level

top number

force of heart pump

• pumping out blood

• maximum arterial pressure during contraction

normal: <= 120 mmHg

diastolic level

bottom number

heart filling up with blood

• minimum arterial pressure during relaxation

<= 80 mm Hg

prehypertension

highest risk of high BP

120-139 mmHg / 80-89mmHg

hypertension stage 1

high BP

140-159 / 90-99

hypertension stage 2

severe high BP

>160 / >100

hypertensive

emergency condition

>=180 / >110

hypertensive crisis

leads to heart attack/stroke/death

hypertension / high BP

silent killer —> 1/3 people don’t know they have —>no symptoms

uncontrollable risk factors

primary and secondary types

uncontrollable risk factors of hypertension

1. genetics

2. age

primary hypertension

aka essential HT

the cause in unknown

• idiopathic

secondary hypertension

results of medical problems or meds

• kidney or liver diseases

physical or physiological

atherosclerosis

blood viscosity

• caused by dehydration / EPO

heart function

• increase HR leads to increase chance of stroke

volume

• amount of blood that the heart out per beat

what contributes to high BP

diet

• high sodium

stress/trauma

obesity

smoking tobacco

• nicotine

caffeine

excessive alcohol

poor sleep

• sleep apnea

arterial blood pressure

rises and falls according to pattern established by cardiac cycle

systolic + diastolic

measured by sphygmomanometer

hypotension

<90/60 mmHg

1. dehydration

2. rapid position changes (orthostatic / sudden drop)

3. pregnancy (preeclampsia)

4. heart failure

5. severe infection (sepsis)

6. allergic reactions

7. meds

• diuretics (water loss - pee a lot)

• beta blockers

• anti depressants

8. nutritional deficiencies

• lack B12 or B9

• food rich in potassium help

APICAL pulse

pulse at the heart

needs the stethoscope

pulse

if pulse is normal: count for 30s and multiply by 2 OR 15s and multiply by 4

normal: 60-100 bpm

if irregular check pulse for one minute

athletes: 40-60bpm

tachycardia

bradycardia

irregularity

Arrythmia

which finger has its own pulse

thumb

• do not use when checking pulse

tachycardia

high pulse

resting over 100bpm

caused by:

• infection

• dehydration

• cardiac condition

bradycardia

low pulse

resting below 60 bpm

caused by:

• drugs

• not athlete

irregularity

Arrhythmia

skipping beats

uneven beats

pulse pressure

difference between systolic + diastolic

• normal difference is 40 mmHg

indirect measurement of cardiac output

diastolic - systolic

low pulse pressure

<25-30

BASH

BASH

low pulse pressure

B LEEDING (hemorrhage)

A ORTIC (largest artery)

S TENOSIS (narrowing of BV)

H EART FAILURE

high pulse pressure

>40

AFAR

high pulse pressure

A THROSCLEROSIS

F EVER

A ORTIC

R REGURGE

what artery is used to measure blood pressure

brachial artery

sphygmomanometer

listens to sound

release pressure = first sound = systolic

after sound = diastolic

3 layers of artery

tunica interna

tunica medai

tunica externa

tunica interna

innermost endothelial layer of artery

prevents platelet aggregation/clumping

secretes substances to regulate blood flow

tunica media

thick middle layer of artery

composed of smooth muscle

tunica externa

outermost CT layer of artery

thin

attaches artery to tissues

sympathetic impulses

innervate the smooth muscle in the walls of arteries + arterioles via vasomotor fibers

vasomotor fibers

autonomic nerve fibers that innervate the vascular smooth muscle of blood vessels to regulate their diameter

• constriction

• dilation

controls blood flow

sympathetic stimulation

causes muscle contraction

results in vasoconstriction of arteries

vasoconstriction

the constriction of arteries

increases peripheral resistance + BP

vasodilation

vasomotor impulses are inhibited

dilation of arteries occur

decreases peripheral resistance and BP

arterial blood pressure points

radial artery

temporal artery

mandibular artery

axillary artery

carotid artery

brachial artery

femoral artery

APICAL pulse

dorsalis pedis artery

factors that influence arterial BP

1. cardiac output

2. blood volume

3. peripheral resistance

4. blood viscosity

cardiac output

directly affects BP

total volume of blood the heart pumps per minute

stroke volume x heart rate

average CO = 70mL/beat x 72 beats/min = 5040mL/min

if stroke volume or heart rate increases, so does the cardiac output

stroke volume

amount of blood discharged from each ventricle with each contraction

about 70mL

heart rate

number of heart beats per min

average is 72 beats/min

cardioinhibitory reflex arc

1. cardiac output increases

2. BP increases

3. baroreceptors in aortic arch + carotid sinuses are stimulated

4. sensory impulses to cardiac center

5. parasympathetic impulses to heart

6. SA node inhibited

7. heart rate decreases

8. BP returns normal (ish)

baroreceptors

sense changes in Bp

located in aortic arch + carotid arteries

cardioinhibitory reflex

in arterial BP increases, baroreceptors send impulses to cardiac center of medulla oblongata

parasympathetic impulses are sent to sinoatrial node to slow heart rate + decrease CO and BP

sinoatrial node

the heart's natural pacemaker

cardioaccelerator reflex

if arterial BP decreases, medulla oblongata sends sympathetic impulses to increase heart rate + CO + BP

some other factors that cause change in BP

emotionally upset

exercise

rise in temperature

peripheral resistance

controls BP

the resistance to blood flow determined by the diameter of small arterioles

• changes in arteriolar diameter changes BP

  • Symphathetic nerves change diameter in response to BP changes

• smaller diameters will provide greater resistance + increase BP

some chemical can impact by affecting precapillary sphincters + smooth muscle

what chemicals affect peripheral resistance

increase CO2 and decreased O2 and decreased pH cause vasodilation in tissues with high metabolic needs

epinephrine and norepinephrine causes vasoconstriction of systemic vessels which increase PR and BP

vasomotor center

in medulla oblongata

adjusts sympathetic impulses of smooth muscles in arterioles

• adjusts BP

contractions of skeletal muscles - vein blood flow

squeeze blood back up veins one section at a time

respiratory movements - vein blood flow

creates differences in thoracic + abdominal pressures which draw blood back up the veins

venoconstriction - vein blood flow

returns blood to heart

initiated by sympathetic reflexes when BP in veins is low

aorta

body’s largest diameter artery

principal branches of aorta

1. ascending aorta

2. aortic arch

3. descending aorta

• thoracic aorta

• abdominal aorta

ascending aorta

first portion

extends out of left ventricle

aortic sinuses are opposite of the valve cusps

region/organ supplied: heart

branch of ascending aorta

right + left coronary arteries

aortic arch

bend of aorta

after ascending aorta

3 branches

3 branches of aortic arch

1. brachiocephalic trunk

2. left common carotid artery

3. left subclavian artery

brachiocephalic trunk region/supplies

right upper limb, right side of head

left common carotid artery region/supplies

left side of head

left subclavian artery region/supplies

left upper limb

descending aorta

follows arch

extends down the anterior to the vertebral column

consists of thoracic aorta and abdominal aorta

thoracic aorta

portion above diaphragm

allows for small arteries to supply thoracic wall and viscera

thoracic aorta branches

bronchial

pericardial

esophageal

mediastinal

posterior intercostal

bronchial artery

thoracic aorta

supplies bronchi

pericardial artery

thoracic aorta

supplies pericardium